Microfludic platforms for the evaluation of anti-platelet agent efficacy under hyper-shear conditions associated with ventricular assist devices

Abstract

Thrombus formation is a major adverse event affecting patients implanted with ventricular assist devices (VADs). Despite anti-thrombotic drug administration, thrombotic events remain frequent within the first year post-implantation. Platelet activation (PA) is an essential process underling thrombotic adverse events in VAD systems. Indeed, abnormal shear forces, correlating with specific flow trajectories of VADs, are strong agonists mediating PA. To date, the ability to determine efficacy of anti-platelet (AP) agents under shear stress conditions is limited. Here, we present a novel microfluidic platform designed to replicate shear stress patterns of a clinical VAD, and use it to compare the efficacy of two AP agents in vitro. Gel-filtered platelets were incubated with i) acetylsalicylic acid (ASA) and ii) ticagrelor, at two different concentrations (ASA: 125 and 250μM; ticagrelor: 250 and 500nM) and were circulated in the VAD-emulating microfluidic platform using a peristaltic pump. GFP were collected after 4 and 52 repetitions of exposure to the VAD shear pattern and tested for shear-mediated PA. ASA significantly inhibited PA only at 2-fold higher concentration (250 μM) than therapeutic dose (125 μM). The effect of ticagrelor was not dependent on drug concentration, and did not show significant inhibition with respect to untreated control. This study demonstrates the potential use of microfluidic platforms as means of testing platelet responsiveness and AP drug efficacy under complex and realistic VAD-like shear stress conditions.

Platelet activation is a preoperative risk factor for the development of thromboembolic complications in patients with continuous‐flow left ventricular assist device

“…Over the last few years, the PAS assay has been utilized extensively for in vitro pre‐clinical studies of device‐associated SMPA . However, no studies have utilized the PAS assay for monitoring SMPA in the clinical setting.…”

“…With this study we also set the basis for the future development of a next‐generation point‐of‐care diagnostic device for bedside and/or home‐based antithrombotic therapy monitoring. Our group has recently reported on the development and use of microfluidic technology to address this aim . Such a system will enhance standardization of the method via automating procedural steps, thus reducing the risk of random/systematic users' errors to affect the results.…”

“…Previous studies have shown that PAS assay correlates well with platelet P‐selectin and annexin V 27,28 expression, as quantified with flow cytometry. Moreover, previous studies have shown that the PAS assay is sensitive to the effect of platelet‐metabolized antiplatelet drugs …”

Cell Damage Index as Computational Indicator for Blood Cell Activation and Damage

“…8, 50 cells per simulation, 10 simulations per channel) and BDI 1 to BDI 3 (Eqs. [2][3][4]. The ranking of channel quality is the same for all blood damage calculations with a maximum deviation between the calculation schemes of less than 3%.…”

Microfluidic flow-based platforms for induction and analysis of dynamic shear-mediated platelet activation—Initial validation versus the standardized hemodynamic shearing device

“…To overcome these limitations, we developed a new computational fluid dynamic-based approach, which allows the design of specific microfluidic channels able to stimulate platelets with dynamic and highly controlled shear stress patterns of differing amplitudes (Dimasi et al, 2015). Utilizing this approach, we demonstrated the feasibility of configuring lFPs to emulate realistic MCSD shear stress conditions (Consolo et al, 2016b); furthermore, these microfluidic platforms were successfully utilized for testing the efficacy of differing antiplatelet agents under hyper-shear conditions (Dimasi et al, 2017). The microfluidic approach, as a result of its ability to employ small sample volumes, its highly controllable working conditions, and the possibility for automation, is an attractive strategy with great potential for precision medicine.…”